224 REPORTS ON INVESTIGATIONS AND PROJECTS. 



ficiently profound to produce a marked drop in body temperature immedi- 

 ately prior to death ; a notable decrease in the pulse-rate a few days after 

 operation, the pulse-rate then remaining at essentially the same level through- 

 out the life of the animal ; a similar fall in the respiration rate ; and a de- 

 crease in the total metabolism as measured by the carbon-dioxide production, 

 the fall in carbon-dioxide production per kilogram of body-weight per hour 

 being still more noticeable owing to the deposition of inert body-fat. With 

 young animals the growth is checked and their infantile characteristics are 

 preserved ; the sexual activity, if not already developed, never develops, and 

 if nearly or quite established it is profoundly affected. The tendency to the 

 deposition of an excessive amount of body-fat is sometimes accompanied by 

 a thickening of the skin and falling of the hair analogous to changes noticed 

 after thyroidectomy. The change in appearance of older animals surviving 

 a nearly complete removal of the hypophysis is hardly noticeable. 



(2) The influence upon metabolism of non-oxidizable material in the intestinal tract. 

 Francis G. Benedict and Louis E. Emmes. Amer. Jour. Physiol., 30, p. 197. 

 1912. 



The early observation that when food passes through the alimentary tract 

 there is an increase in the energy requirement of the body has received sev- 

 eral explanations. Of these the one strongly supported by Professor Zuntz 

 and his scholars is that the mechanical movements of the intestinal tract in 

 the digestion of foods is the primary cause of this increase in metabolism. 

 This conception was strongly substantiated by a series of observations made 

 by Loewy in the Zuntz laboratory on the effect of a dilute solution of sodium 

 sulphate, which provoked a powerful peristaltic effect and, according to 

 Loewy's experiments, resulted in a very greatly increased metabolism. The 

 importance of this fundamental explanation of the increase in metabolism 

 due to food ingestion called for a repetition of these experiments with mod- 

 ern technique and with greater care as to the control and registration of the 

 extraneous muscular activity of the subject. The experiments were made 

 with the small respiration apparatus used in the Nutrition Laboratory, 

 graphic records were made of the muscular activity, the pulse-rate was 

 continually recorded, and ideal subjects were used. The ingestion of 15 

 grams of crystallized sodium sulphate in 200 c.c. of water resulted in a 

 powerful peristaltic action, but in no increase in the carbon-dioxide excre- 

 tion or oxygen consumption, nor was there any measurable increase in gen- 

 eral of the pulse-rate. The inference is that when suitable precautions are 

 taken for the control of the extraneous muscular activity, the ingestion of 

 sodium sulphate, notwithstanding the intense peristalsis, does not materially 

 increase the gaseous metabolism of the body as a whole. 



On the supposition that an intestinal activity involving segmentation rather 

 than powerful peristaltic waves might result in a larger metabolism, the sub- 

 jects were given varying amounts of agar-agar which produced voluminous 

 stools and obviously called for more mechanical work through the process of 

 segmentation. In the ideally controlled experiments there was no measura- 

 ble increase in the carbon-dioxide output or oxygen intake. 



It appears, therefore, from the results obtained in this series of experi- 

 ments, that although the movements along the intestinal tract of a bulky 

 material such as agar-agar, taken either in jelly form or with water, is 

 accomplished without the expenditure of any considerable or measurable 

 amount of energy, yet the "work of digestion," in so far as either peristalsis 

 or segmentation is concerned, can not be of sufficient moment to play an 



